saft: update 'flashrom_util' to use new syntax

Using 'iotools' to control flashrom target is obsoleted.
The new parameter provided by 'flashrom' utility is better and prevents potential
race condition, so all scripts using flashrom should apply the new syntax.

BUG=chromium-os:11339
TEST=passed SAFT on CR48 (by josephsih)

Change-Id: Ia5f7d7ea3bc087b4506a101407a21087b4e278b7

Review URL: http://codereview.chromium.org/6594114
1 file changed